中文摘要：

审计市场竞争的性质及在竞争环境中会计师事务所的行为与绩效是审计研究领域的一个重要议题，产业组织分析的结构主义为此提供了有用的框架。规模经济、产品差异性和服务多元化是决定审计市场结构的三个主要因素。审计市场中可能的规模经济在于审计师行业知识累积过程中的“干中学”效应和行业专家的某种程度上的“资产专用性”；审计的产品差异性包括审计意见质量差异、信号传递功能差异和保险功能差异；审计与咨询服务之间的交叉补贴使得服务多元化改变审计的收费、成本以及审计市场的结构。与西方国家不同，目前我国审计市场结构呈现出低集中度、分散与分割的特征，但已有的研究未能给出基于制度背景的系统解释。

英文摘要：

The nature of competition in the market for audits and CPA firms＇ behavior and performance in this competitive environment are an important topic in audit research area. This paper, based on structuralism, discusses the three determinants of audit market structure： economies of scale, product differentiation and diversification. Possible economies of scale in audit market are due to the ＂ learning by doing＂ effect during the auditor＇s industrial knowledge accumulating process and certain degrees of asset specificity of industry specialist. Audit product differentiation can include quality differentiation of audit opinion, signaling function differentiation and insurance function differentiation. Consulting services may affect the price and cost of audit services and the whole audit market structure because of the existence of cross-subsidizing between audit and consulting services induced by economies of scope and knowledge spillovers. Current Chinese audit market structure has three special characteristics, decentralization, partition and low concentration. These characteristics are greatly different from that of Western developed audit market, but researchers haven＇t systematically provided institutional explanations by following structuralism. For this reason, some important research directions in the Chinese audit market are also discussed in this paper. Potential valuable research topics include： （1） Is the competition between CPA firms efficient competition or inefficient competition？ （2） What is the impact of the merger of China＇s CPA firms on audit market structure？ Can it lead audit market to higher concentration？ （3） What competitive strategy do international ＂big four＂ apply in the Chinese audit market？ Is it a response to the special audit market structure？ （4） As Chinese CPA firms become larger and larger, what characteristics will appear in the aspects of economies of scale, product differentiation and diversification？